a. Field of the Invention
The present invention relates to a retrofocus type lens system having ultra-wide angle of view and long back focal length.
B. Description of the Prior Art
Retrofocus type lenses having ultra-wide angle of view exceeding 90.degree. and long back focal length have a such a common nature that meridional image surface, distortion and lateral chromatic aberration are undercorrected at intermediate angle of view when such aberrations are favorably corrected at marginal angles of view and, on the other hand, such aberrations are overcorrected at marginal angles of view when they are favorably corrected at intermediate angle of view. It is therefore difficult to correct the above-mentioned aberrations both at intermediate and marginal angles of view and, in the present circumstances, it is managed to correct the aberrations by increasing lens components to enhance flexibility for correcting the aberrations. Since lens systems are generally so designed as to correct aberrations for objects at infinite distance, meridional image surface is remarkably varies to extremely degrade resolution of image at marginal portion when the lens systems are focused on objects at short distances.